The construction of a building structure traditionally comprises three stages:
(i) earthscraping; PA1 (ii) construction of an underground foundation structure; PA1 (iii) construction of building structure atop said foundation structure.
A building structure is designed to carry vertical loads arising from the weight of the actual structure including the contents therein and associated normative mobile forces, and these loads are conventionally supported by a foundation structure which is rigidly embedded underground. However, traditional building construction methods and techniques have, in the main, proved inadequate in preserving the structural integrity of such structures during and following the application of strong horizontal forces, such as arise from seismic shocks for example, as is evident from the extensive structural damage suffered by many buildings during the recent Los Angeles and Kobe earthquakes. Typically, a strong horizontal force acting on a building structure tends to induce a toppling moment on the structure, causing at least part of the underground foundation structure to become uprooted, thereby irreversibly destabalising the upper structure, and causing partial or total collapse of the building structure. Furthermore, the phenomenon of liquefaction, common with earthquakes, is also responsible for widespread damage. The shaking of the ground causes soil to settle, driving gas and water towards the surface, reducing the ability of foundation structures to support buildings. Furthermore, the foundation structures become destabilised and are weakened, leading to the disintegration of the same and of the building structures atop them.
Attempts have been made to render buildings "earthquake-resistant", for example by increasing the strength of a given building structure, particularly by the incorporation of additional steel reinforcement within a reinforced-concrete type of structure. However, increasing the ability of a building structure to resist the effects of an earthquake may only provide a limited solution, since seismic forces greater than the design magnitude for any particular building, resisted by a relatively inflexible structure, will lead to major structural damage, even total collapse, of the same.
Newsweek magazine (Jan. 30, 1995) discusses alternative earthquake-resistance techniques including "seismic isolation", in which a building lies on top of steel and rubber pads, which effectively minimise relative movement between the structure and foundation; the pads act as shock absorbers, reducing the amount of ground motion that gets transmitted to a structure during an earthquake. Nevertheless, though the building may further be designed to be flexible in order to absorb some of the energy associated with the seismic shock by swaying, there still remains a substantial element of resistance against the swaying, ultimately leading to structural damage if the shock is strong enough. Furthermore, the foundation structures are still rigidly embedded underground, albeit "insulated" from it to a degree, and may suffer the same fate as conventional buildings if a large-enough seismic shock is applied thereto. Additionally, such techniques do not provide adequate protection against liquefaction, wherein one part of the foundation may experience more movement than another part, leading to the eventual disintegration of the same.
An aim of the present invention is to provide a foundation structure for building structures and the like which is substantially earthquake-proof while not being subject to the above-mentioned limitations.
A further aim of the present invention is to provide a suitable building support structure onto which a predetermined--including conventional--building structure, may be mounted, which enables the same to "ride out" the effects of a predetermined horizontal force to a much greater extent than is possible with conventional or flexible building structures.
A further aim of the present invention is to provide a suitable building support structure wherein the impact energy associated with the application of a strong horizontal force on same may be effectively dissipated by the conversion of said energy into rotation kinetic energy of said support structure by the rolling motion thereof, thereby minimising corresponding impact stresses on, and substantially preserving the structural integrity of, said building support structure including any predetermined ancillary structure that may be optionally rigidly attached thereto, further enabling the same to roll back to substantially the same position and attitude that existed prior to application of said force.
A further aim of the present invention is to provide a suitable building support structure onto which a building structure may be mounted, wherein said building support structure may roll along and/or be displaced along the ground, while providing structural support for said building structure.
A further aim of the present invention is to provide a building structure comprising an integral building support structure having any or all of the above-mentioned characteristics.
A further aim of the present invention is to provide a method for building an earthquake-proof building support structure for a building structure.
A further aim of the present invention is to provide a method for building a single earthquake-proof building support structure for a plurality of building structures.
A further aim of the present invention is to provide a method for building an earthquake-proof building structure.
Briefly stated, these aims are accomplished via a revolutionary approach to the support of building structures, wherein rather than following the traditional method of setting building structures atop static foundations rigidly embedded in the ground, an above-ground dynamic support structure enables building structures to be supported while remaining independent of the ground, thereby effectively permitting relative movement to occur between the building structure and the ground. Thus, said building support structure, rather than stiffly resisting a seismic shock applied thereto, is able to ride out the effects of the shock, by using the momentum imparted to it by the shock, and therefore the associated energy of same, to initiate movement of the building support structure over the surface, including reversible rolling about a horizontal axis over the same and optionally including translation over same and/or rotation about a vertical axis over the same, thereby dissipating the energy of the seismic shock in a more controlled manner than hitherto possible, thus substantially maintaining the structural integrity of the building structure.